The present invention relates to the field of crime prevention. More particularly, the apparatus prevents misappropriation of electronic devices. Even more particularly, the apparatus seeks to frustrate an automobile thief by disabling the target vehicle's ignition system.
Numerous devices have been devised to prevent motor vehicle theft, including those disclosed in U.S. Pat. Nos. 3,907,060; 4,037,557; 4,071,007; 4,300,495; 4,452,197; 4,545,345; Japanese Patent Nos. 53-66996; 55-151706; and Great Britain Patent No. 1,259,941. Each of these prior art devices utilize owner operable switching means to disable the motor vehicle ignition system. Typically, such systems are turned on and off by manually operated switches mounted in hidden or obscure places in the driver's compartment. The switches are normally mounted in the glove compartments or beneath the dashboards where they are obscured from view, yet conveniently accessible to those who know of their existence and location. If the vehicle owner throws the switch, the anti-theft circuitry is activated to interrupt the ignition circuitry or to disable a key engine starting component.
In practice, these devices are only marginally effective against an experienced auto thief. When a thief seeks to start a motor vehicle and is confronted by a completely dead ignition system, a search for the obscure control switch is immediately initiated. Only a limited number of easily accessible master control switch locations are available in the interior of an automobile, so a practiced thief usually locates the switch after a brief search. Most professional auto thieves acquire quite extensive knowledge of motor vehicle wiring configurations while playing their trade, and may easily bypass any ignition foiling device. Many recent auto anti-theft systems incorporate a loud alarm system which may be activated by such a by-pass attempt. However, these alarms may also be easily disconnected by an experienced practitioner. Conventional theft prevention circuitry is thus only an inconvenience for the professional thief, and is effective only by lengthening the time required for misappropriation of the vehicle.
Some inventors sought to remedy the above dilemma by designing increasingly complex anti-theft circuits incorporating digital computer logic or computer activated servo systems. These devices may be more effective against theft, but reliability problems and complex arming procedures engendered numerous owner complaints. In addition, perplexing diagnostic and repair problems arise in the event of a system malfunction. Such complexity increases costs and necessitates factory installation. None of the known motor vehicle anti-theft devices are totally satisfactory in terms of economy, efficiency and simplicity.